Method for winding electric coils and electric coils produced thereby

ABSTRACT

Electric coils having closely packed turns are wound on a former composed of a tubular body and spaced-apart flanges extending out from the body and defining an annular space on which the coil is wound. The body of the former has a substantially flat crossing face that is defined between substantially straight, spaced-apart lines of intersection between the surface of the body and two angularly related radial-axial planes of the body. Each turn of each layer of wire in the coil is wound with the wire axis centered on a plane perpendicular to the axis of the body of the former in all portions of the turn except for that portion which overlies the crossing face. In the portion of each turn overlying the crossing face, the wire is displaced in a direction parallel to the axis of the body a distance equal to a predetermined pitch distance between the wires of the respective layers. The end of the wire that begins the coil overlies the crossing face, and concavities are provided in each face of the flange in the zones subtended by the angularly related planes that define crossing face, the concavities receiving portions of the wire where the last turn of one layer changes into the first turn of the next layer. The former on which the coil is wound has notches that guide and position the first layer wound on the former.

[4 1 Dec. 3, 1974 i 1 METHOD FOR WINDING ELECTRIC COILS AND ELECTRIC COILS PRODUCED THEREBY [76] Inventor: Maurice Barthalon, Tournepierre Avenue des Sapins, Verrieres Le Buisson, Essonne, France [22] Filed: Apr. 24, 1973 [21] Appl. No.: 353,958

[] Foreign Application Priority Data Apr. 25, 1972 France 72.14619 [52] US. Cl 242/7.03, 242/1 18.4, 336/189 [51] Int. Cl.... HOIf 41/04, I-IOlf 27/28, Bh /14 [58] Field of Search 242/7.03, 7.02, 7.15, 7.16,

[56] References Cited UNITED STATES PATENTS 1,504,005 8/1924 Vienneau 242/7.03 1,935,975 11/1933 Donandt 242/117 2,559,824 7/1951 Leland 140/922 3,109,601 1l/1963 Van Der Hoek et a1 242/7.03 3,391,879 7/1968 Le Bus, Sr. 242/117 3,480,229 ll/l969 DEntremont 242/1 18.4

Primary ExaminerBilly S. Taylor Attorney, Agent, or FirmBrumbaugh, Graves, Donohue & Raymond 5 7] ABSTRACT Electric coils having closely packed turns are wound on a former composed of a tubular body and spacedapart flanges extending out from the body and defining an annular space on which the coil is wound. The body of the former has a substantially flat crossing face that is defined between substantially straight,

spaced-apart lines of intersection between the surface of the body and two angularly related radial-axial planes of the body. Each turn of each layer of wire in the coil is wound with the wire axis centered on a plane perpendicular to the axis of the body of the former in all portions of the turn except for that portion which overlies the crossing face. In the portion of each turn overlying the crossing face, the wire is displaced in a direction parallel to the axis of the body a distance equal to a predetermined pitch distance between the wires of the respective layers. The end of the wire that begins the coil overlies the crossing face, and concavities are provided in each face of the flange in the Zones subtended by the angularly related planes that define crossing face, the concavities receiving portions of the wire where the last turn of one layer changes into the first turn of the next layer. The former on which the coil is wound has notches that guide and position the first layer wound on the former.

20 Claims, 13 Drawing Figures METHOD FOR WINDING ELECTRIC COILS AND ELECTRIC COILS PRODUCED THEREBY BACKGROUND OF THE INVENTION One type of winding machine known heretofore comprises a guide that is moved in a direction parallel to the winding axis in a controlled manner in that the movement parallel to the axis of the coil being wound is a function of the rotation of the former on which the coil is wound, the control being such as to produce a winding having closely packed turns. In coils made on those machines, the first layer of turns is frequently somewhat irregular, principally as a result of the presence of the lead-in end of the wire that forms the beginning of the coil. Inasmuch as turns of the wire of the successive layers are located within the spaces between the turns of the previous layer, any disorder in the original or first layer formed on the former progressively increases from one layer to the next. Another problemwith such machines is that each turn in each layer of the coil must cross over a turn or turns of the previous layer at least at one point in each turn. Since each turn nests over most of the perimeter of the coil in a space between previous turns, thus producing a total thickness of two layers that is less than twice the diameter of the two wires while, at the same time, each cross over point involves a minimum thickness equal to twice the diameter of the wire, there are points of greater thickness in a portion of each turn of each layer constituted by the crossing points where'a turn of one layer crosses a turn of another layer. In-known machines, the positions of the crossing points are not controlled and occur in a random and erratic manner. Accordingly, the coil tends to develop with an irregularvtotal thickness because of the random location of zones of greater thickness due to the random distribution of cross over points.

Some efforts have been made heretofore in known winding machines to provide adjustments which are performed by the machine operator that minimize variations in the thickness of the coil. Another solution that has been tried is to place an insulator of substantial thickness between each layer. Both of the techniques for controlling thickness variation in a coil substantially increase the price and in some instances the total size of the winding. Moreover, the addition of relatively thick insulators between the layers substantially reduces the dissipation of heat from within the coil during operation.

SUMMARY OF THE INVENTION There is provided, in accordance with the present invention, a method and apparatus for winding electric coils, and an electric coil produced thereby, which overcome the problems of known machines and the efforts made to solve the problem of thickness variations.

More particularly, in accordance with the invention,

electric coils having closely packed turns are wound on a former having a tubular body and spaced-apart flanges extending out from the body and defining an annular space between them where the coil is wound.

The body of the former has a substantially flat crossing maintaining each turn of the wire in each layer of the coil substantially in a plane perpendicular to the axis of the body of the former in all portions of such turn, except for the portion which overlies the crossing face, and displacing each turn in each layer a predetermined pitch distance in a direction parallel to the axis of the body substantially exclusively in said portion thereof which overlies the crossing face. In other words, the axes of the major portions of each turn of each layer lie in planes substantially perpendicular to the axis of the coil, and all portions of each turn of each layer which cross corresponding portions of underlying layers overlie the crossing face.

In a preferred embodiment, the former on which the coil is wound is provided with guiding and positioning notches at least along each edge adjacent each line defining the crossing' face. The notches are uniformly spaced apart a distance equal to the pitch distance between the turns of each layer of the coil. Preferably, the distance between each turn is not less than and not substantially greater than a distance equal to the diameter of the wire and preferably is between 1.00 and 1.04 times the diameter of the wire. Such a pitch distance provides mutual contact between the sides of the wires (or a very small spacing between the wires). Corresponding notches at each edge of the crossing space lie in a common plane that is perpendicular to the axis of the former, thereby insuring that the portions of the turns in areas that do not overlie the crossing face of the former are centered on planes perpendicular to the axis of the former. The notches may extend continuously on planes perpendicular to the axis of the former between the edges of the crossing face. Preferably, the end notches immediately adjacent one flange of the former are centered on a plane that is spaced a distance from the flange that is equal to one-half the pitch distance of the series of notches, while the end notches adjacent the other flange of the former are spaced a distance from the other flange equal to the pitch distance between the notches. I

Each flange of the former is preferably provided with a concavity in its inner face, the concavity lying within a zone defined between lines of intersection between the face of the flange and the aforementioned radialaxial planes that define the crossing face. The concavities allow the portions of the wire where the last turn of one layer merges into the first turn of the next layer to make a smooth transition from one layer to the next, each transition portion being partially received within the concavity. Moreover, the starting end of the wire where the coil begins is preferably received in the concavity and overlies the crossing portion of the tubular body of the former.

For a better understanding of the invention and the advantages it provides, reference may be made to the following description of exemplary embodiments taken in conjunction with the Figures of the accompanying drawings.

DESCRIPTION OF THEDRAWINGS FIG. 1 is a pictorial view of an end portion of one embodiment of a former used for winding the coil;

FIG. 2 is a pictorial view of the former shown in FIG. 1, the view being on a smaller scale than in FIG. 1 and the former being shown in a different orientation from that of FIG. 1;

. v 3 FIG. 3 is a side view in cross-section of the former shown in FIGS. 1 and 2;

. FIG. 4 is an end view in cross-section of the former shown in FIG. 1 3, the view being taken generally along a line IV--IV of FIG. 3 in the direction of the arrows;

FIG. 5 is a partial longitudinal cross-sectional view of guide notches provided on the former illustrated in FIGS.1 4;'

FIG.,6 is a fragmentary cross-sectional view taken generally along the lines VI-VI in FIG. 4 and in the direction of the arrows;

FIG. 7 is a half longitudinal cross-sectional view of a former having layers of a coil wound on it, a portion of the view being broken out to reduce the size of the view, and the view being taken at a zone of the coil outside of the crossing face; FIG. 8 is a cross-sectional view, also with a center portion broken out, taken just outside the beginning portion of a second layer of wire wound on the former and viewing the zone overlying the crossing face of the former;

FIG. 9 is a partial longitudinal cross-sectional view similar to the view of FIG. 7 except illustrating the cross-section at a portion along the crossing face, as

designated generally by the lines lX-IX of FIG. 8 and DESCRIPTION OF EXEMPLARY EMBODIMENT In the embodiment illustrated in FIGS. 1 9 of the drawings, the coil is woundon a coil former that is composed of a tubular body 1 having, in transverse cross-section, a rectangular shape (see FIG. 4) and two flanges 2 and 3 which are substantially rectangular and are positioned at the ends of the tubular body. The

1 body and the two flanges define an annular space onto which a wire is wound to form the coil. The crosssectional shape of the tubular body and the shapes of the flanges may, of course, be varied in accordance with the desired cross-sectional shape of the coil. In the embodiment, itshould be evident that the resulting coil wound on the former will be substantially rectangular in cross-section. The lines designated by the letters XX in FIG. 1 represent the axis of the tubular body 1 of the former. Radial-axial planes, that is planes that extend radially and include the axis X ofthe former, intersect the surface of the tubular body along lines that define on the surface of the body a substantially flat crossing face 4, bhe two imaginary radial-axial planes intersecting at an angle. In the embodiment, the lines of intersections just referred to constitute the edges where the flat faces of the rectangular tubular body intersect. However, a flat crossing facedefined by straight lines of intersection between radial-axial, angularly' related planes is an important feature of the inven- The embodiment of the former illustrated in F IGS. 1

spaced notches 5 located at each edge where the facesof the tubular body intersect. In accordance with the invention, such notches will be provided at least along both edges of the crossing face of the former and often will extend continuously between the edges in the portion of the tubular body of the former outside of the crossing face. Corresponding notches at either edge of the crossing face are located in common planes perpendicular to the axis XX of the former. As may be seen from FIG. 5 of the drawings, the notches in the embodiment of FIGS. 1 9 are V-shaped with the pitch dis tance P measured in a direction parallel to the axis of the former between the centers 6 of the notches being equal to the pitch distance between the turns of the wire. As illustrated in FIG. 7, the center lines 6a of the first notches adjacent one of the flanges 2 of theformer are spaced a distance from that flange (flange 2) equal to one-half of the pitch distance between the notches, that is, adistance P/2, where P designates the pitch distance. The center line 6b of the end notch along each edge of the crossing face 4 adjacent the other flange 3 of the former is equal to the pitch distanceP. The significance of the pitch distances and particularly the distances between the center lines of the first and last notches in each row and the flanges is explained below. The first notch is designated by the reference number 5a, and the last notch is designated by the reference number 5b in FIG. 7. I

The internal face of each of the flanges 2 and 3 of the former is providedwith a concavity 7 and 8, the respective concavities in the flanges being defined generally by the intersections between the internal faces of the flanges and the imaginary angularly related, radial-axial planes that also define the crossing face 4 (see FIG. 4

of the drawing). The concavities may be uniformly curved, with a flatter curvature in portions farther away throughout their radial extent. The depth at the base of tion parallel to the axis XX of the body in the direc- 9 of the drawings has a multiplicity of uniformly I each form of concavity, measured at a direction paral- Iel to the axis XX of the body 1 of the former, should be between about P/3 and P/l.5. The internal face of each flange in the area outside of the'concavity should be flat and lie in a plane perpendicular to the axis XX. i

The method of forming a coil onthe former involves rotating the former about its axis XX and guiding the wire being wound so as to maintain the portion of the wire being pulled onto the coil in a substantially fixed position when the wire is being applied against that portion of the coil overlying the surface of the former outside of the crossing face and-moving the wire in a direction of the next turn of the wire over a distance equal to the pitch P between the notches during the time that the wire is being applied against the crossing face 4. More particularly, referring to FIG. 8 of the drawings, the coil is started by leading the end 10 of a wire out through a hole 9 in the flange 2 of the former, which flange isadjacent to the notch 5a that is centered onehalf pitch distance from the flange. The hole 9'is located generally at the center of the concavity 7 in the flange 2, which is also a central location adjacent the crossing face 4. The former is then rotated to draw the starting portion of the first turn 11 of the wire into the first notch 5a of the former. The portion 1 1a of the wire which overlies the crossing face 4 resides in the concavity 7 and lies flat against the crossing face 4. The wire guide is-then held stationary as the former rotates about its axis so that the first turn of the wire around the portion of the body of the former outside of the crossing face 4 has its axis aligned on a plane perpendicular to the axis XX of the former. Accordingly, the wire reaches the first notch 5a on the other edge of the crossing face 4. As the former rotates through an angle which takes the wire across the crossing face 4, the wire lying that part of the body outside of the crossing face is guided in a direction parallel to the axis XX a distance equal to the pitch distance P so that the wire is received in the next notch 5 at the opposite edge of the crossing face.

Each additional turn of the'first layer progresses in the manner described above, namely, by holding the wire guide stationary as it is laid on the former body in the zone outside of the crossing face and then guiding the wire in a direction parallel to-the axis XX of the former a distance equal to the'pitch distance P during the time that the wire is laid on the crossing face 4. Thus, the first layer comprises turns of wire, each of which includes a'portion outside of the crossing face where the axis of the wire lies in a plane perpendicular to the axis XX of the former and a portion overlying the crossing face 4 in which the wire is located at an angle to a perpendicular plane and is shifted one pitch distance P parallel to the axis XX of the former from one edge to the other edge of the crossing face 4 in the direction of the progression of the turns on the layer.

At the end of the first layer formed on the body of the former a transition turn 14 is produced. The transition turn 14 begins at the end of aportion of the preceding turn in which the axis of the turn in the region outside of the crossing face lies in the plane perpendicular to the axis XX of the former, the end of such portion residing in the last notch 5b at the edge of the crossing face. As the wire is drawn onto the crossing face 4 it is guided in a direction toward theflange 3 parallel to the axis XX a distance equal to one-half P. A portion 14c of the turn 14 lies against the crossing face 4 and is received in the concavity 8 on the interface of the flange 3, butas the wire progresses across the face 4 it begins to ride up on the preceding turn of the layer, since the space between the preceding turn and the face of the flange is no longer adequate to accommodate all of the wire. By the end of the portion of the transition turn 14 4 in which the wire lies in a plane perpendicular to the axis XX of the former and a crossing portion in which the wire is shifted one pitch distance parallel to the axis XX in that portion of the turn overlying the crossing face 4.

As illustrated in FIG. 7 the turns of each layer in portions of the circumference of the coil lying outside the zone bounded generally by the radial-axial planes defining the edges of the crossing face are staggered so that the turns of a given layer are centered between the turns of the layers below and above the given layer (see FIG. 7). The portion of each turn of each layer overlying the crossing face 4 crosses over two turns of the layer underlying it and crosses under two turns of a layer overlying it. As illustrated in FIG. 9, therefore, the turns of the respective layers in the coil overlying the crossing face 4 are stacked one above the other. Thus, the thickness of the coil in the zone lying outside of the zone overlying the crossing face is somewhat less than the-sum of the diameters of the number of layers of the coil, while the thickness of'the coil in the zone overlying the-crossing face is generally equal to the in which the wire overlies the crossing face 4 a portion 14b of the transition turn is nested between the flange 3 and the preceding turn of the wire. From the portion 14b around to the portion 14d of the transition turn, the axis of the wire lies substantially in a plane perpendicular to the axis XX of the former with one edge of such portion supported against the flange 3 and another portion of the wire nesting against the preceding turn.

The next turn 15 of the wire begins by shifting the wire parallel to the axis XX during the time that the wire is pulled across the face 4, a distance equal to one pitch distance P, the direction being opposite from the lay of the first layer, as is evident from FIG. 8. From this point on, the winding procedure progresses as in the first layer in that each turn includes a portion overnumber of turns multiplied by the diameter of the wire. The former may, accordingly, be dimensioned and shaped to provide a substantially uniform overall shape to the coil. Moreover, the invention provides the production of a coil having a maximum packing of the turns without any chance for disorder or disruption in the arrangement of the turns.

Among the variations and modifications in the invention are the opportunities for numerous variations in the shape of the former and in the shapes of the notches. For example, FIG. 10 shows a tubular body 16 which is substantially circular in cross-section, except for the flat crossing face 17. The embodiment of FIG. 10 also has notches 18 that extend continuously from one edge to the other edge of the crossing face 17. As shown in FIGS. 11 and 12 the shapes of the notches may be varied: For example, they may be curved as represented by the notches 21 shown in FIG. 11 or generally rectangular, as indicated by the notches 22 shown in FIG. 12.

The above-described embodiments of the invention are intended to be merely exemplary, and the foregoing and other variations and modifications of the invention will be apparent to those skilled in the art without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as defined in the appended claims.

I claim:

l. A method of winding electric-coils having closely packed turns on a former having a tubular body and a pair of spaced-apart flanges on the body between which the coil is wound, the body of the former having a substantially flat crossing face defined between substantially straight spaced-apart lines of intersection between the surface of the body and angularly related radial-axial planes of the body, each flange having a concavity on its inwardly facing surface the edges of which are defined by lines of intersection between the inner, flat surface of the flange which is substantially perpendicular of the axis of the tubular body, comprising the steps of maintaining each turn of the wire in each layer of the coil substantially in a plane perpendicular to the axis of the body of the former in all portions of such turn except that portion which overlies the crossing face, displacing each full turn in each layer a predetermined pitch distance in a direction parallel to the axis of the body substantially exclusively in said portion thereof which overlies the crossing face, and advancing the wire from the last turn of one layer to the first turn of the next following layer by displacing it radially away from said axis of the tubular body substantially exclusively within the concavity of one of the flanges.

2. A method according to claim 1 wherein the winding of the coil is started with an end portion of the first turn of the bottom layer overlying the crossing face.

3. A method according to claim 1 wherein the wire is led from the last turn of one layer to the first turn of the next following layer by displacing it substantially exclusively at the crossing face a distance substantially equal to one half of said predetermined pitch distance.

4. A method according to claim 1 wherein said predetermined pitch distance is a distance not less than the diameter of the wire and is not substantially greater than the diameter of the wire.

5. A method according to claim 4 wherein said predetermined pitch distance is between about 1.00 and about 1.04 times the diameter of the wire.

6. Amethod according to claim 1 further comprising the step of guiding the wire through guide notches on the body of the former on which the coil is wound, the notches being uniformly spaced apart a distance substantially equal to said on the body beginning by laying the end portion of the wire on the crossing face adjacent one flange, maintaining each turn of the wire in the first layer of the coil substantially in a plane perpendicular to the axis of the body of the former in all portions of such turn except that portion which overlies the crossing face, the axis of the wire between the turns being spaced a distance not less than and not substantially. greater than the thickness of the wire, displacing each full turn in the first layer a predetermined pitch distance in a direction parallel to the axis of the body and away from said one flange substantially exclusively in said portion thereof which overlies the crossing face, displacing the wire from the last turn of the first layer a distance in a direction parallel to the axis and toward said one flange of the body equal to one-half of said predetermined pitch distance substantially exclusively in said portion thereof within said concavity which overlies the crossing face, and laying a second layer of wire over the first layer in which all portions of each turn except that portion which overlies the crossing face lie in planes perpendicular to the axis of the body of the former and in which each turn is displaced a distance equal to the pitch distance in a direction parallel to the axis and toward said one flange of the body substantially exclusively in the portion thereof which overlies the crossing face.

7. A method according to claim 6 further comprising the step of beginning the coil in a first notch adjacent one flange of the former the medial axis of the first notch being located a distance from that flange substantially equal to one-half of said predetermined pitch distance.

8. A method according to claim 1 in which the maximum depth of each concavity measured along a line parallel to the axis of the body of the former is between P/3 and P/ 1.5 where P designates said predetermined pitch distance.

9. A method of winding electric coils having closely packed turns on a former having a tubular body and spaced-apart flanges extending from the body between which the coil is wound, each flange of the former having on its inwardly facing surface a concavity the edges of which are defined by lines of intersection between an inner surface of the flange which surface isflat and substantially perpendicular to the axis of the tubular body, and the said pair of angularly related radial-axial planes, the body of the former having a substantially flat crossing face defined between substantially straight spaced-apart lines of intersection between the surface of the body and angularly related radial-axial planes of the body comprising the steps of winding a first layer of the wire on the body beginning by laying the end portion of the wire on the crossing face adjacent one flange, maintaining each turn of the wire in the first layer of the coil substantially in a plane perpendicular to the axis of the body of the former in all portions of such turn except that portion which overlies the crossing face, the axis of the wire between the turns being spaced a distance not less than and'not substantially greater than the thickness of the wire, displacing each full turn in the first layer a predetermined pitch distance in a direction parallel to the axis of the body and away from said one flange substantially exclusively in said portion thereof which overlies the crossing face, displacing the wire from the last turn of the first layer a distance in a direction parallel to the axis and toward said one flange of the body equal to one-half of said predetermined pitch distance substantially exclusively in said portion thereof within said concavity which overlies the crossing face, and laying a second layer of wire over the first layer in which all portions of each turn except that portion which overlies the crossing face lie in planes perpendicular to the axis of the body of the former and in which each turn is displaced a distance equal to the pitch distance in a direction parallel to the axis and toward said one flange of the body substantially exclusively in the portion thereof which overlies the crossing face.

10. In apparatus for winding an electric coil having closely packed turns, a former onto which the coil is wound comprising a tubular body having a substantially flat crossing face defined between substantially straight spaced-apart lines of intersection between the surface of the body and a pair of angularly related radial-axial planes of the body; pair of spaced-apart flanges extending outwardly from the body to define therebetween with the body an annular space adapted to receive the coil, each flange having a concavity on its inwardly facing surface, the edges of the concavity being defined by lines of intersection between an inner, flat surface of the flange which is substantially perpendicular to the axis of the tubular body and the pair of angularly related radial-axial planes and wire-guiding and located notches uniformly spaced and located at least at the edges of the crossing face adjacent said lines of intersection, the medial axes of corresponding notches along each edge being located in common planes perpendicular to the axis of the body, the spacing between the notches being at a predetermined pitch distance that is not less than and is not substantially greater than the diameter of the wire to be wound on the former.

11. Apparatus according to claim wherein said pitch distance between the notches is between about 1.00 and about 1.04 times the diameter of the wire to be wound on the former.

12. Apparatus according to claim 10 in which the medial axis of the first notch at each edge of the cross ing face of the former and adjacent one flange of the former is located a distance from said one flange substantially equal to one-half of the pitch distance between the notches and wherein the medial axis of the last notch at each edge of the crossing face and adjacent the other flange of the former is located a distance from said other flange substantially equal to the pitch distance.

13. Apparatus according to claim 10 wherein the tubular body of the former is of rectangular cross section in planes transverse to its axis and wherein there are wire-guiding and locating notches at each of the corners thereof, the axes of corresponding notches at each other corner being located substantially in the same plane, which plane is perpendicular to the axis of the body.

14. Apparatus according to claim 10 wherein there are notches extending substantially continuously from one edge of the crossing face to the other edge of the crossing face in the portion of the tubular body outside of the crossing face.

15. Apparatus according to claim 10 wherein the depth of each concavity, measured in a direction parallel to the axis of the tubular body of the former, does not exceed a depth of P/l.5, where P designates the predetermined pitch distance, at any region thereof.

16. Apparatus according to claim 1 wherein the said predetermined depth is between P/3 and P/l.5, where P designates the predetermined pitch distance between the notches formed in the body.

17. An annular electric coil comprising a multiplicity of layers of wire overlying each other in succession,

each of which layers has a multiplicity of turns, the major portion of each turn of each layer lying in a plane perpendicular to the axis of the coil, allsuch portions of all turns being located outside of a crossing zone subtended by a pair of angularly related radial-axial planes of the coil, and each turn of each layer including a portion located entirely within the crossing zone in which the wire crosses portions of two turns of the layer immediately underlying it, all turns of all wires crossing each other only in the crossing zone of the coil, the layers of the coil being wound on a former comprising a tubular body having a flange at either end, the inner surface of each flange being flat except for a concavity on the inner surface of each flange within the crossing zone, the transition of the wire from one layer of the coil to the next overlying layer occurring within the concavity of the flange.

18. A coil according to claim 17 wherein the beginning of the first layer lies within the crossing zone.

19. A coil according to claim 18 wherein all turns of each layer are centered a distance apart measured parallel to the axis of the coil not less than and not substantially greater than the diameter of the wire and the portions of each turn of each layer (except the innermost layer) outside of the crossing zone are centered between the turns of the next underlying layer.

20. A method according to claim 6 further comprising the step of guiding the last turn of the first layer of the coil through a notch adjacent each said line of intersection and a flange of the former, the notch being located a distance from the flange substantially equal L-LUJJ mg STAS first ores unit 5 esonN invemm-(s) Maurice Barthalon It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 5 7, "bhe" should read --the-; w

Column 6, line 40, change the semicolon to a period;

Column '7, line 32, after "said" delete the balance of claim 6 and substitute therefor; -pitch distance, the notches adjacent each said 7 line of intersection being correspondingly located 4 to be centered on common planes perpendicular to the axis of the body.---;

Column 9, line 20, "other" should read ----s1.ich--:

Column 9, line 33, "claim 1" should read --claim lO-; and

Column 10, line 8', after "layer" insert --(except.,the innermost layer)--.

Signed and sealed this 18th day of February 1975.

(SEAL) Attest: v v

T C. MARSHALL DANN v RUTH C... MASON issioner of Patents Attesting Officer and Trademarks -l-UJJ $21 33 UFD STATES Patent names QERTEHQATE @F @REEQTE@N" Patent 3,851,836 Datefi December 3,, 1974 inventcfls) Maurice Barthalon It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 57, "bhe" should read --the-;

Column 6, line 40, change the semicolon to a period;

Colmnn 7, line 32, after "said" delete the balance of claim 6 and substitute therefor; -pitch distance, the notches adjacent each said i line of intersection being correspondingly located to be centered on common planes perpendicular to the axis of the body.--;

Column 9, line 20, "other" should read --such--;

Column 9, line 33, claim 1 should'read --claim l0-; and

Column 10, line 8', after "layer" insert -(except,the innermost layer)--.

Signed and sealed this 18th day of February 1975,

(SEAL) Attest:

. C. MARSHALL DANN RUTH Co MASON Commissioner of Patents Attesting Officer and Trademarks 

1. A method of winding electric coils having closely packed turns on a former having a tubular body and a pair of spacedapart flanges on the body between which the coil is wound, the body of the former having a substantially flat crossing face defined between substantially straight spaced-apart lines of intersection between the surface of the body and angularly related radial-axial planes of the body, each flange having a concavity on its inwardly facing surface the edges of which are defined by lines of intersection between the inner, flat surface of the flange which is substantially perpendicular of the axis of the tubular body, comprising the steps of maintaining each turn of the wire in each layer of the coil substantially in a plane perpendicular to the axis of the body of the former in all portions of such turn except that portion which overlies the crossing face, displacing each full turn in each layer a predetermined pitch distance in a direction parallel to the axis of the body substantially exclusively in said portion thereof which overlies the crossing face, and advancing the wire from the last turn of one layer to the first turn of the next following layer by displacing it radially away from said axis of the tubular body substantially exclusively within the concavity of one of the flanges.
 2. A method according to claim 1 wherein the winding of the coil is started with an end portion of the first turn of the bottom layer overlying the crossing face.
 3. A method according to claim 1 wherein the wire is led from the last turn of one layer to the first turn of the next following layer by displacing it substantially exclusively at the crossing face a distance substantially equal to one-half of said predetermined pitch distance.
 4. A method according to claim 1 wherein said predetermined pitch distance is a distance not less than the diameter of the wire and is not substantially greAter than the diameter of the wire.
 5. A method according to claim 4 wherein said predetermined pitch distance is between about 1.00 and about 1.04 times the diameter of the wire.
 6. A method according to claim 1 further comprising the step of guiding the wire through guide notches on the body of the former on which the coil is wound, the notches being uniformly spaced apart a distance substantially equal to said on the body beginning by laying the end portion of the wire on the crossing face adjacent one flange, maintaining each turn of the wire in the first layer of the coil substantially in a plane perpendicular to the axis of the body of the former in all portions of such turn except that portion which overlies the crossing face, the axis of the wire between the turns being spaced a distance not less than and not substantially greater than the thickness of the wire, displacing each full turn in the first layer a predetermined pitch distance in a direction parallel to the axis of the body and away from said one flange substantially exclusively in said portion thereof which overlies the crossing face, displacing the wire from the last turn of the first layer a distance in a direction parallel to the axis and toward said one flange of the body equal to one-half of said predetermined pitch distance substantially exclusively in said portion thereof within said concavity which overlies the crossing face, and laying a second layer of wire over the first layer in which all portions of each turn except that portion which overlies the crossing face lie in planes perpendicular to the axis of the body of the former and in which each turn is displaced a distance equal to the pitch distance in a direction parallel to the axis and toward said one flange of the body substantially exclusively in the portion thereof which overlies the crossing face.
 7. A method according to claim 6 further comprising the step of beginning the coil in a first notch adjacent one flange of the former the medial axis of the first notch being located a distance from that flange substantially equal to one-half of said predetermined pitch distance.
 8. A method according to claim 1 in which the maximum depth of each concavity measured along a line parallel to the axis of the body of the former is between P/3 and P/1.5 where P designates said predetermined pitch distance.
 9. A method of winding electric coils having closely packed turns on a former having a tubular body and spaced-apart flanges extending from the body between which the coil is wound, each flange of the former having on its inwardly facing surface a concavity the edges of which are defined by lines of intersection between an inner surface of the flange which surface is flat and substantially perpendicular to the axis of the tubular body, and the said pair of angularly related radial-axial planes, the body of the former having a substantially flat crossing face defined between substantially straight spaced-apart lines of intersection between the surface of the body and angularly related radial-axial planes of the body comprising the steps of winding a first layer of the wire on the body beginning by laying the end portion of the wire on the crossing face adjacent one flange, maintaining each turn of the wire in the first layer of the coil substantially in a plane perpendicular to the axis of the body of the former in all portions of such turn except that portion which overlies the crossing face, the axis of the wire between the turns being spaced a distance not less than and not substantially greater than the thickness of the wire, displacing each full turn in the first layer a predetermined pitch distance in a direction parallel to the axis of the body and away from said one flange substantially exclusively in said portion thereof which overlies the crossing face, displacing the wire from the last turn of the first layer a distance in a direction parallel to the axis and toward said one flange of the body equal to one-half of said predetermined pitch distance substantially exclusively in said portion thereof within said concavity which overlies the crossing face, and laying a second layer of wire over the first layer in which all portions of each turn except that portion which overlies the crossing face lie in planes perpendicular to the axis of the body of the former and in which each turn is displaced a distance equal to the pitch distance in a direction parallel to the axis and toward said one flange of the body substantially exclusively in the portion thereof which overlies the crossing face.
 10. In apparatus for winding an electric coil having closely packed turns, a former onto which the coil is wound comprising a tubular body having a substantially flat crossing face defined between substantially straight spaced-apart lines of intersection between the surface of the body and a pair of angularly related radial-axial planes of the body; pair of spaced-apart flanges extending outwardly from the body to define therebetween with the body an annular space adapted to receive the coil, each flange having a concavity on its inwardly facing surface, the edges of the concavity being defined by lines of intersection between an inner, flat surface of the flange which is substantially perpendicular to the axis of the tubular body and the pair of angularly related radial-axial planes and wire-guiding and located notches uniformly spaced and located at least at the edges of the crossing face adjacent said lines of intersection, the medial axes of corresponding notches along each edge being located in common planes perpendicular to the axis of the body, the spacing between the notches being at a predetermined pitch distance that is not less than and is not substantially greater than the diameter of the wire to be wound on the former.
 11. Apparatus according to claim 10 wherein said pitch distance between the notches is between about 1.00 and about 1.04 times the diameter of the wire to be wound on the former.
 12. Apparatus according to claim 10 in which the medial axis of the first notch at each edge of the crossing face of the former and adjacent one flange of the former is located a distance from said one flange substantially equal to one-half of the pitch distance between the notches and wherein the medial axis of the last notch at each edge of the crossing face and adjacent the other flange of the former is located a distance from said other flange substantially equal to the pitch distance.
 13. Apparatus according to claim 10 wherein the tubular body of the former is of rectangular cross section in planes transverse to its axis and wherein there are wire-guiding and locating notches at each of the corners thereof, the axes of corresponding notches at each other corner being located substantially in the same plane, which plane is perpendicular to the axis of the body.
 14. Apparatus according to claim 10 wherein there are notches extending substantially continuously from one edge of the crossing face to the other edge of the crossing face in the portion of the tubular body outside of the crossing face.
 15. Apparatus according to claim 10 wherein the depth of each concavity, measured in a direction parallel to the axis of the tubular body of the former, does not exceed a depth of P/1.5, where P designates the predetermined pitch distance, at any region thereof.
 16. Apparatus according to claim 1 wherein the said predetermined depth is between P/3 and P/1.5, where P designates the predetermined pitch distance between the notches formed in the body.
 17. An annular electric coil comprising a multiplicity of layers of wire overlying each other in succession, each of which layers has a multiplicity of turns, the major portion of each turn of each layer lying in a plane perpendicular to the axis of the coil, all such portions of all turns being located outside of a crossing zone subtended by a pair of angularly related radial-axial planes of the coil, and each turn of each layer including a portion located entirely within the crossing zone in which the wire crosses portions of two turns of the layer immediately underlying it, all turns of all wires crossing each other only in the crossing zone of the coil, the layers of the coil being wound on a former comprising a tubular body having a flange at either end, the inner surface of each flange being flat except for a concavity on the inner surface of each flange within the crossing zone, the transition of the wire from one layer of the coil to the next overlying layer occurring within the concavity of the flange.
 18. A coil according to claim 17 wherein the beginning of the first layer lies within the crossing zone.
 19. A coil according to claim 18 wherein all turns of each layer are centered a distance apart measured parallel to the axis of the coil not less than and not substantially greater than the diameter of the wire and the portions of each turn of each layer (except the innermost layer) outside of the crossing zone are centered between the turns of the next underlying layer.
 20. A method according to claim 6 further comprising the step of guiding the last turn of the first layer of the coil through a notch adjacent each said line of intersection and a flange of the former, the notch being located a distance from the flange substantially equal to said predetermined pitch distance. 